Field of the Invention
The present invention relates to a toner used in electrophotography, in image-forming methods for visualizing electrostatic images, and in toner jets.
Description of the Related Art
Toner that can support a higher speed, higher image quality, longer life, and better energy conservation than in the past has come to be required in recent years in association with the development of image-forming apparatuses such as copiers and printers. Lowering the fixation temperature of a toner is effective for achieving energy conservation in, for example, a copier or printer, and toner that melts at lower temperatures is thus required. In addition, the use environment for toners has been undergoing diversification, and toner is thus required that can deliver a stable image even when used in a variety of environments.
Adjusting the melt viscosity of the binder resin—which is the major component of a toner—downward is known as a method for causing a toner to melt at a lower temperature. However, the durability of a toner is reduced when the melt viscosity of the binder resin itself is adjusted downward. As a result, after long-term use in a high-temperature, high-humidity environment, the amount of charge can undergo large fluctuations due to toner deterioration and density non-uniformity in halftone images (referred to as halftone non-uniformity in the following) may be produced. Various investigations have therefore been carried out into methods that do not lower the melt viscosity of the binder resin itself, but rather cause the toner to melt at a lower temperature through the addition of a plasticizer.
Japanese Patent Application Laid-open No. 2001-13714 proposes a method of controlling the melting characteristics of a toner through the use of a low melting point wax.
Japanese Patent Application Laid-open No. 2015-175858 proposes a toner that can cope with a broad fixation temperature region due to the incorporation in the toner of at least 6 mass % and not more than 17 mass % of bisphenoxyethanolfluorene.
Japanese Patent Application Laid-open No. 2008-165005, on the other hand, discloses a binder resin that uses bisphenoxyethanolfluorene as one of the monomers constituting the binder resin used in toner.